1. Field of the Invention
This invention relates to marking equipment and more particularly to rotary head markers which are power driven.
2. Prior Art
Rotary head markers have been frequently used in industry for imprinting indicia on a workpiece. A common type of rotary marker includes a rotating head which has indicia on the circumference thereof which is alternately brought into contact with an inking roll and the workpiece, the inking roll being positioned parallel to, and angularly displaced from, the workpiece surface. Such imprinters are frequently used in connection with film printing where a roll of film which is later to be used as packaging for a product is unrolled past the marker, positioned either at a separate imprint station where it is re-rolled after being imprinted by the marker or in connection with the packaging or filling machine which is being fed by the film. In such instances it is known to utilize preprinted film where the area to be imprinted by the marker represents only a small portion of the individual film panel with the film comprising a longitudinally extending series of panels with each of the panels forming a face of the eventual package.
In such marking devices, and particularly those marking devices in which the rotary head is power driven as opposed to being driven by contact with the workpiece, it is necessary to align the imprint from the marker head with the area of the panel designated to receive the imprint and further with the spacing between designated areas on adjacent panels. Spacing has frequently been varied through the use of different diameter heads or by the use of drive trains for the rotation of the head which vary the speed of rotation of the head. In the latter instance, however, it is important that when the indicia is in contact with the workpiece that both the indicia and workpiece are moving at an identical rate of speed in order to prevent smearing. It has been suggested to vary the rotation speed of the head so that the speed of rotation of the head varies during each complete revolution of the head whereby at the times when indicia are in contact with the workpiece the head will be rotating at a speed equal to the movement of the film past the rotating head while at times when the indicia are out of contact with the workpiece the head is rotating at a greater or lesser speed producing a difference in movement of the indicia and movement of the film. In this manner, spacing between individual imprints can be varied.
It also has been known to adjust the positioning of the imprint with respect to the individual panels by varying the gearing position between the drive to the film transport mechanism and the drive to the rotating head such that the rotation of the head with respect to the film position can be initially adjustably preset.
Heretofore such adjustment possibilities, however, have involved complex variations in the preset condition of the machinery or in the position of the rotating head on its drive shaft or in the drive train. Such adjustments could not easily be made while the machinery was in operation, and added considerably to the maintanence and initial cost of the imprinter assembly. It would therefore be an advance in the art to provide a simple rotary imprint mechanism capable of on the fly, i.e., while operating, adjustment of both imprint position and successive indicia speed.